1. Field of the Invention
This invention relates to devices for venting gas in a gas delivery system and, more particularly, to an improved venting device for safety venting gas in metering vaults.
2. Prior Art
In recent years, heating and cooking equipment utilizing natural or manufactured gas has been changing so as to eliminate the continuously-running pilot light which has been characteristic of such devices in the past. This step has, of course, come from the general drive for increased conservation of natural resources and in most gas-fired devices being manufactured today, the pilot light no longer exists. Instead, electrical spark means are provided to light the gas on demand. Of course, not everybody has switched to the newer devices and some still have pilot lights in their gas-fired equipment. As a result, there is a tendency to have differences in pressure at the sites of the various consumers, a condition which is not to be tolerated. It has become necessary in many of these systems, for example, in the gas distribution system of the Southern California Gas Company in Los Angeles, to install internal relief valve (IRV) regulators. These IRV regulators release, through an internal relief valve, downstream pressure build-up. Such regulators are, however, installed in curb vaults which have limited space. It has been determined by tests conducted in Los Angeles that with a mere 1.0 cubic foot per hour leakage rate arising from the relief process referred to hereinbefore, the gas/air ratio in a vault will reach the lower explosive limit of 4.5% concentration of the heating gas. It was apparent that the ventilation in existing curb vaults was not sufficient to vent the gas being released by the new IRV regulators.
Engineers in the field tried to solve the problem of the dangerous accumulation of gas released by the relief valves, by increasing the number of slots found in the covers on the vaults enclosing the relief valves. If this expedient had been relied upon, hundreds of thousands of slotted covers would have had to have been replaced in the system at a great expense. Further, because the new slotted vault covers would differ from those which had been previously approved by the local governing bodies, great time and money would have had to be expended in obtaining the approvals which would be needed before the new slotted vault covers could have been installed. During that delay, a dangerous condition would exist in the distribution system.
Therefore, it is an object of the present invention to overcome the various problems which have been set forth hereinbefore.
It is a further object of this invention to provide a venting device which will be inexpensive to fabricate and install and will accomplish the needed ventilation of gas arising from internal relief valves necessarily being installed in gas distribution systems.